CNN is canceling John King’s daily show “John King, USA,” the ailing news network said yesterday.

King’s show will end June 29, and Wolf Blitzer’s “The Situation Room” will be extended to three hours to replace King’s time slot at 6 p.m., CNN said. The decision comes in the face of slumping ratings for CNN.

Last month, the network fell to a 20-year low in primetime, attracting fewer than 400,000 viewers — a 51 percent drop from the same period in 2011.

Reports that the network is on the verge of a major shakeup have been circulating.

King, 48, who joined CNN in 1997 and served as White House correspondent before getting his own show in 2010, was routinely the lowest-rated show on the evening schedule.

He will now appear on other CNN shows.

CNN said the changes would bolster its coverage of the 2012 race to the White House — though the statement made little sense since King was based in DC and his program was about politics.

“John is an exceptional reporter, and we want him to be available to report for more shows and to be out in the field, as he did in the last election season,” a spokeswoman said.